Unprotected sex

I'm 18 almost 19 and this the the first guy I ever had sex with. We've been dating six months now. So we've had sex a few times without condoms and he always pulls out right before he cums. The only thing I'm worried about is pre-cum. Every other time has been protected but lately my boobs feel really heavy and sore. I'm just really nervous and don't know what to do.